Electronic devices (cellular telephones, wireless modems, computers, digital music players, Global Positioning System units, Personal Digital Assistants, gaming devices, etc.) have become a part of everyday life. Small computing devices are now placed in everything from automobiles to housing locks. The complexity of electronic devices has increased dramatically in the last few years. For example, many electronic devices have one or more processors that help control the device, as well as a number of digital circuits to support the processor and other parts of the device.
An electronic device may include one or more integrated circuits. These integrated circuits may include analog and digital circuitry necessary for wireless communication.
As electronic devices become more expensive, designers look to reduce costs by reducing the number of components and/or the board area used by components. If a component can be removed or shared, the cost of the electronic device may be reduced. By integrating components onto integrated circuits, electronic devices may be built that are smaller, faster, cheaper and that use less power. However, such integrated circuits have a limited number of pins for access to the circuitry. Thus, benefits may be realized by using circuitry that provides access to circuitry without requiring the use of additional pins.